Lecture Notes: The Pancreas

Introduction

• Major role in human health
• Significant increase in Type 2 diabetes predicted in next 10-20 years

Functions of the Pancreas

• Endocrine Function:

  • Directly into the bloodstream
  • Involves insulin and glucagon
  • Insulin:
    • Opens channel proteins in cells
    • Allows sugar into cells, reducing blood sugar
  • Glucagon:
    • Released during hypoglycemia
    • Taps into sugar reserves in muscles and liver
    • Breaks glycogen into glucose for ATP production

• Exocrine Function:

  • Uses ducts to empty secretions
  • Focus of current discussion

Pancreatic Anatomy

• Pancreatic Ducts:
  • Composed mainly of pancreatic acinar cells
  • Release pancreatic juice into pancreatic duct
  • Two main ducts: accessory duct and main pancreatic duct
  • Joins with common bile duct

Duct System

• Common Bile Duct:

  • Formed by left and right hepatic ducts, empties into common hepatic duct
  • Gallbladder empties bile into bile duct
  • Joins with the pancreatic duct at the ampulla

• Ampulla and Papillary Structures:

  • Major and minor duodenal papilla
  • Major and accessory pancreatic ducts join bile duct
  • Empty into duodenum of small intestine

Regulation of Pancreatic Juices

• Sphincter of Oddi:
  • Regulates flow into duodenum
  • Acts as a valve

Pancreatic Enzymes

• Break down macromolecules: carbohydrates, fats, proteins, nucleic acids
• Examples:
  • Pancreatic Amylase: Breaks down starch to disaccharides
  • Pancreatic Lipase: Breaks down lipids into glycerol and fatty acids
  • Trypsin: Activated by enterokinase, breaks down proteins
  • Chymotrypsin and Carboxypeptidase: Activated by trypsin, break down proteins
  • Nucleases: Breaks down nucleic acids

Role of Bicarbonate Ions

• Neutralize stomach acid in the small intestine
• Prevents digestion of intestinal walls

Hormonal Regulation

• Secretin:
  • Stimulates pancreas to release bicarbonate-rich juices
• Cholecystokinin (CCK):
  • Stimulates enzyme-rich gastric juices

Nervous System Involvement

• Parasympathetic System:
  • Enhances digestion under rest-and-digest conditions
  • Reduced activity under stress, leading to upset stomach

Conclusion

• Overview of pancreatic functions and anatomy
• Next topic: Liver and Gallbladder